Improve error message for sigv4 and PermanentRedirect errors

The error message now includes a note on specifying the
correct region:
```
 $ aws s3api list-objects --bucket wrong.region.bucket

 A client error (PermanentRedirect) occurred when calling the ListObjects operation:

 The bucket you are attempting to access must be addressed using the specified
 endpoint. Please send all future requests to this endpoint:
 wrong.region.bucket.s3-ap-southeast-2.amazonaws.com
 You can fix this issue by explicity providing the correct region location
 using the --region argument, the AWS_DEFAULT_REGION environment variable, or
 the region variable in the AWS CLI configuration file.  You can get the
 bucket's location by running "aws s3api get-bucket-location --bucket BUCKET".
```

Same thing when you try to access a bucket in eu-central-1.

cc @danielgtaylor @kyleknap 
Will the endpoint be the full name of the endpoint or will it be the name of the region? I could see this being confusing if it gives back the full name of the endpoint. But should be ok if the user just uses the ``get-bucket-location`` command.